Biocompatibility and crystal growth of poled hydroxyapatite ceramics and coatings

摘要

Bone-like crystal growth and biological behavior on the electrically poled hydroxyapatite and it's coating films were investigated. Sintered hydroxyapatite and plasma sprayed hydroxyapatite coatings on titanium plate were used as specimens. These specimens were electrically poled in a dc field of 1 to 1000V/cm for 1h at 300 deg C. Crystal chemistry of the poled specimens were investigated by X-ray diffraction and thermal analysis. Bone-like crystal growths were studied in a simulated body fluid (SBF) with pH=7.25 at 36.5 deg C, and in Eagle's minimum essential medium with osteoblastic cells. Grown crystal layers were observed by scanning electron microscopy, and were analyzed by X-ray diffraction and Infrared spectroscopy. As a result, the bone-like hydroxyapatite crystals grew rapidly on the negatively poled surface, while the growth was restricted on the positively poled surface in SBF. Hydroxyapatite films prepared by different methods had the same effects of poling. It was considered that the aligned dipoles of substrate accelerated the crystal growth on the negative-pole surface, and decelerated on the positive-pole surface.